Genotypic variation in pigeonpea for yield, photosynthetic rate and p uptake at varying phosphorus levels

Genotypic variation in ten pigeonpea genotypes was studied at three P levels (100%, 60% and 20% P as per nutrient solution) in the pot culture house. The plant biomass decreased with decreasing P levels and the decline was highest at the reproductive stage. The genotypes which performed well in terms of plant biomass were Paras and H03–41. Decline in number of leaves and branches could account for the decreased plant biomass at low P levels. The photosynthetic rate and chlorophyll content were adversely affected by low P levels. The genotypes H03–41, H04–24, ICPL 88039 and Paras maintained higher photosynthetic rates as compared to other genotypes at low P levels. The flowering was delayed by 1–5 days at 20% P levels in the different genotypes studied. The genotypes H03–41, H02–60, H0122 and Paras performed better in terms of P concentration per plant as compared to other genotypes. A 35 to 60% decline in plant yield was observed at 20% P levels. Maximum decline was observed in the genotypes H01–14, H01–22 and H01–37 whereas minimum decline was observed in the genotypes H03–41, H04–26 and Paras.